Data linkage for RDAREAs using the inner replica facility

With Datareplicator, you can also use HiRDB's inner replica facility to link data in RDAREAs.

When the inner replica facility is used, the update log is always output to the system log file whether the updated RDAREA is the original or a replica. Datareplicator extracts from this update log the log information corresponding to the source table ID.

If the target database uses the inner replica facility, you can import the data into the current RDAREA that is subject to data linkage (original or replica RDAREA) or into a specific generation of the database. You cannot specify a different target for each table. To import data into a specific database generation, specify the database with HiRDB's PDDBACCS environment variable.

The following figure shows data linkage for RDAREAs using the inner replica facility.

Figure 3-19 Data linkage for RDAREAs using the inner replica facility

[Figure]

Organization of this subsection: (1) Data linkage definitions for inner replica; (2) Limitations

(1) Data linkage definitions for inner replica

To specify the method for extracting update log information, use the extract_level operand described in 5.3 Extraction environment definition. The relationship between the extract_level operand value and the update log information to be extracted is as follows:

current_gen: When the source HiRDB uses the inner replica facility, extract only the updating of the current RDAREA.
all_gen: When the source HiRDB uses the inner replica facility, also extract the updating of all replica RDAREAs (including the original RDAREA).

Use the following guidelines to specify the extract_level operand based on the handling of inner replica:

Handling of inner replica	extract_level operand value
The current RDAREA is always the master (source subject to extraction).	Specify extract_level=current_gen.
An RDAREA other than the current RDAREA can be the master (source subject to extraction).	Specify extract_level=all_gen when the disk is disconnected^#.

#: Some limitations apply to the specification of extract_level=all_gen. For details, see (2) Limitations.

The following are guidelines for specifying the extract_level operand:

[Figure]

(2) Limitations

For updating of the event table (event issuance), the update information for all generations is extracted, regardless of the source Datareplicator's definitions.
For PURGE TABLE, if extract_level=current_gen is specified, the Datareplicator extracts only PURGE TABLE whose RDAREAs are all current RDAREAs.
For the RDAREA subject to data linkage, specify current_gen as the extraction level for the current RDAREA if possible.
To use the replica RDAREA subject to data linkage as a non-current RDAREA, specify all_gen as the extraction level. In this case, updates on all replica RDAREAs are extracted regardless of whether they are subject to data linkage; therefore, updating a replica RDAREA that is not subject to data linkage results in inconsistent data linkage. When you set the extraction level to all_gen, make sure that only the replica RDAREAs subject to data linkage are updated. The following example shows inconsistent data linkage that occurs when the extraction level is set to all_gen:
To change the source replica RDAREA that is to be extracted, the replica RDAREA must be synchronized with the target database. The following shows the procedure for changing the replica RDAREA subject to extraction:

3.2.9 Data linkage for RDAREAs using the inner replica facility

(1) Data linkage definitions for inner replica

(2) Limitations